Equivalent mortality and complication rates following periprosthetic distal femur fractures managed with either lateral locked plating or a distal femoral replacement.

INTRODUCTION: Management of distal femur fractures above total knee arthroplasty (TKA) remains challenging. Two common surgical options are locked lateral plating (LLP) and distal femoral arthroplasty (DFR). Unfortunately, approximately 30-50% of patients may die within one year of injury, require further surgery, or not regain prior mobility performance. We compared 87 LLP to 53 DFR patients - to our knowledge the largest comparative study - focusing on 90- and 365-day mortality, mobility maintenance, and further surgery.

METHODS: We performed a retrospective review of patients at least 55 years old who sustained femur fractures near a primary TKA (essentially OTA-33 or Su types 1, 2, or 3) from 2000 to 2015 assigning cohort based on treatment: LLP or DFR. We excluded patients having prior care for the injury, whose surgery was not for fracture (e.g. loosening), or having other surgical intervention (e.g. intramedullary nail).

RESULTS: Results Cohorts were similar based on body mass index and age adjusted Charlson Comorbidity Index (aaCCI). LLP was more common than DFR for fractures above and at the level of the implant, but similar for fractures within the implant for patients with aaCCI ≥ 5. LLP and DFR had similar mortality at 90 days (9% vs 4%) and 365 days (22% vs 10%), need for additional surgery (9% vs 3%), and survivors maintaining ambulation (77% vs 81%). Patients whose surgery occurred 3 or more days after presentation had similar mortality risk to those whose surgery was before 3days. The mean age of one year survivors was 77 whereas for patients who died it was 85. Neither surgical choice nor aaCCI was associated with increased risk in time to surgery.

CONCLUSIONS: Fracture location, remaining bone stock, and patient's prior mobility and current comorbidities must guide treatment. Our study suggests that 90- and 365-day mortality, final mobility, and re-operation rate are not statistically different with LLP vs DFR management.